Looking at the date, this might be solved already but for others crossing this situation:
you should be able to assing a CONST num variable to the array size. If you do this, you just have to change the value of the CONST num if you want another size array.
You cannot change CONST vars at run time though, so if you want another array you should change the CONST value at the start of the program.
Also, as far as I know it is not possible to define arrays dynamically.